1. Field of the Invention
The invention is based on the detection and matching of tempo and phase in pieces of music, especially for the realisation of an interactive music player, which amongst other advantages, allows several synchronised pieces of music to be played back to form a complete new work. In this context, digital music data are obtained, according to one advantageous embodiment, by a playing back several pieces of music at the same time on a standard CD-ROM drive in real-time.
2. Related Background Art
In present-day dance culture, which is characterised by modern, electronic music, the technical demands on the disc jockey (DJ) have increased to a considerable extent. Sorting the pieces of music to be played to form a complete work with its own characteristic curve of emotional excitement (referred to as a set or a mix) is one of the standard tasks required of a DJ. In this context, it is important to be able to match the individual pieces of music with reference to their tempo and the phase, in other words, the position of the beats in the time grid, (referred to in English as “beat matching”), in such a manner that the pieces of music merge in a unified manner at the transition points without interrupting the rhythm.
This requirement presents the technical problem of tempo and phase matching of two pieces of music and/or audio tracks in real-time. Accordingly, it would be desirable if the tempo and phase of two pieces of music and/or audio tracks could be matched automatically in real-time, in order to release the DJ from this technical aspect of mixing, and/or to create a mix automatically or semi-automatically, without the assistance of a technically skilled DJ.
So far, this problem has only been addressed in an incomplete manner. For example, software players are available for the MP3 format (a standard format for compressed digital audio data), which can realise pure, real-time tempo detection and matching. However, phase detection must still be carried out manually on the basis of the listening and matching skills of the DJ. This demands a considerable amount of the DJ's attention, which would otherwise be available for more artistic aspects such as compiling the music etc.
Hardware effects-equipment for processing audio information, which can indeed realise real-time tempo and phase detection is also already known, but this equipment cannot match the tempo and phase of the audio material, if the data have only been supplied in analogue form. The equipment can only provide a visual display of the relative phase shift of the two audio tracks.
However, no devices are currently known which utilise tempo information to calculate loops (short audio segments, which can be played back repeatedly) and loop lengths. With the previously used playback equipment, these are either cut and loaded in advance (software MP3 player) or set and matched manually (hardware CD player).
Accordingly, one object of the present invention is to create the possibility for automatic tempo and phase matching of two pieces of music and/or audio tracks in real-time with the greatest possible accuracy.
One substantial technical problem here is the accuracy of tempo and phase measurement, which declines in direct proportion to the time available for measurement. The primary problem is therefore to establish the tempo and phase in real-time, as, for example, in the case of live mixing.